The present invention relates to a device for inserting a reinforced introducing point of a sliver into a spinning unit of a rotor spinning machine.
Several devices exist for inserting a new sliver into a spinning unit of a rotor spinning machine by connecting the end of a new sliver to the end of a sliver that has already been inserted into the spinning unit and spun. This connection can be summarized as follows: a feeler for monitoring the sliver that is situated under the spinning unit determines if the sliver being spun has been cut or interrupted and in turn stops the spinning process. A portion of the sliver is withdrawn such that a sufficiently long sliver end hangs from the condenser hole of the spinning unit. When the original textile can is replaced by a new, full can having another sliver end positioned in a holder located on the can, the two sliver ends are grasped by a mechanism and connected by interlacing. The spinning unit is started again for continuing the spinning process and the newly joined sliver is inserted into the spinning unit.
Another known device for inserting the end of an adapted sliver into a spinning machine is a device wherein the end of the sliver is gripped between a pair of rotating rollers and inserted into the condenser hole by the revolving motion of the rollers.
The drawbacks of these known devices include the necessity to install a sliver presence monitoring feeler at each operating station (spinning station) of a rotor spinning machine which requires a modification of existing spinning units. This constitutes a considerable drawback when automating the sliver process operation.
Other drawbacks include the difficulty encountered in ensuring a constant quality connection of the two sliver ends.
Fluctuations in the quality of the connection lead to sliver ruptures when it is drawn into the spinning unit, and thus cause a defect that cannot be repaired by the operating device. The quality of the yarn section produced from the connection of the sliver ends is also affected. First, the yarn fineness changes to such an extent that in the subsequent processing this section is considered as a quality defect in the fabric. Since the end of the original sliver and the length of the connecting section of sliver, together, make a sliver length which cannot be combed out of the rotor in one attempt, the sliver can only be removed by repeatedly cleaning the rotor.
A drawback also exists where the adapted sliver end is gripped in a pair of revolving rollers because there is considerable distance between the gripping point of the revolving rollers of the gripper and that of the feed roller and the table of the spinning unit which requires the adapted sliver end to be stiffer. Again, in case of high-speed rotor machines with small diameter rotors, the adapted sliver end cannot be combed out of the rotor at one time by suction prior to being spun by the spinning machine, thus causing yarn quality fluctuations.